prolly been done to death - K&N v Paper filter

[lazlokovacs]

well there's a lot of to and fro out there on that innernet regarding the merits of K&Ns vs stock paper filters on vehicles equipped with airboxes, a real passionate game of "who's right" where it seems that everyone loses....

but very little in the way of statistical evidence.

So.... anyone out there in the trusted guzziverse have any views on the pros and cons?

regarding flow, and filtration?

Or better still any dyno run evidence?


Coupla things I already know - pods are cooler than an aribox

                                         - Some airboxes are restrictive
                                         
                                         - a guzzi will rarely be particularly fast 

                                         - changing airflow usually means changing carburation


thanks as ever!

[twowings]

Snake oil. Period.

[pyoungbl]

If you want the machine to run correctly (power wise, not EPA wise) the airbox volume becomes important.  The intake creates harmonics which can boost performance to match the exhaust.  Pods eliminate the airbox advantages, period.  A K&N filter might flow more air but to do so it surely fliters out fewer of the fine particles.  From a practical standpoint this is probably a moot point because few of us will own a particular motorcycle long enough to see the damage those tiny particles are doing to the rings, bore, and bearings.  For the Guzzi owners (you know who you are) that do run a bike for 100+K miles, what has been your experience?

On the V7 with Heron heads I cannot see any benefit to trying to flow more air since the basic head design creates its own limitation to flow.

Peter Y.

[Huzo]

My Norge is 140,000 k and I recently went to Pete's, to have the TB's done and Beetled.
He took the K&N and ( with my permission), "threw it to the shithouse".
An Aussie expression for " discarded it in the direction of the ablution block".
He'll be along to say why he thinks so.
It made good sense when explained.
Also.
If you " flow more air", won't you then necessarily need more fuel to keep the mixture right ?

[LowRyter]

The big advantage of K&N is that they are reusable. Clean them and keep them. Only purchase once. 

[pete roper]

Labyrinth filters are shite.

The end.

Also the cost argument is a total red herring! How many paper filters can you buy before you equal the cost of the rock strainer? How many miles will that equate to?

Pete

[LowRyter]

I hate it when when folks aren't clear about their thoughts.

I wished they would just spit it out. 

[antmanbee]

I use a foam sock filter between the two velocity stacks.
I do this not because I believe the performance is better. I don't know if it is or is not. My bikes pull strong at all RPMs and are plenty fast for me.
I am not overly concerned about the minuscule differences in particle filtration as I ride almost always on paved roads in not dusty conditions.

The primary reason I do it is for ease of servicing and freeing up space. I have easy access to just about everything without that damn airbox.
I also like the intake sound which is incidental to me.

I did read an interesting thread on the Suzuki Savage forum about airbox flow testing with different filters.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1523302904

[lazlokovacs]

thanks for all the opinions...

truly grateful

and I don't doubt the wisdom


/\ antman thanks for the link

.................ca n anyone else point to any evidence?

[beetle]

Using K&N as an example, tests have proven that the filter material doesn't actually improve air flow. This is due to the turbulence created on the manifold side of the filter. However, the actual greater surface area of the filter has a total net increase in air flow.  Contrary wise.





Furthermore, a still airbox proved axactly that, relatively still air. Pod filters have the double whammy of providing worse flow, plus the outside turbulence reduces positive air intake due to the pressure differential adjacent to the pod. For engines with relatively narrow and long intake tracts like a Guzzi, this affect is somewhat less detrimental in certain circumstances.

Air flow affects manifold pressure (or vacuum, if you like). In engines equipped with a MAF (mass air flow) sensor, the ECU can compensate somewhat. For carbs, you re-jet, but as carbs are only good for the one air temperature, air pressure and engine temperature, YMMV.

This means crap for Guzzi's, since the do not have MAF sensors. The single throttle body engines of the V7 and Cali 1400 have MAP (manifold absolute pressure) sensors. They can adjust based on the vacuum difference between stock and rock strainer filters.





The K&N increases the pressure differential (from ambient) compared to a paper filter, so the ECU adjusts fuel. For pre MAP sensor engines (ie CARC and earlier), there is no adjustment made by the ECU because there is no sensor. CARC throttle bodies were flow benched in the factory, hence the "sacred" screw. The ECU has no way to adjust for different flows. To that end, the single throttle body engines respond somewhat better to rock strainers than earlier models.


Actual filtration is far worse in the K&N. Particulate impedance is about 50% that of a paper element.






Says it all, in my opinion.


Anecdotally, the 140 HP Aprilia Tuono uses a physically smaller paper element compared to 100 HP Griso. There is no Guzzi engine that will benefit from a rock strainer There is no valid reason, in my opinion to use anything but a stock paper element.


Thanks for reading.






*charts from:
 Effect  Of  OEM  Style  And  Aftermarket  Performance Air Filters  On Vehicle  Parameters. Mathews  V Johna,*, Sandhya  Ma, Balakrishnan  Ka
 

[SED]

My LMIII came to me with pods and it would occasionally pop through the carb when cracking the throttle open.  Replaced idle jets, slides, floats, needles, advance springs, coils, throttle and cables, rubber carb manifolds, choke plungers...   :Beating_A_Dead_Hors e_by_liviu

Finally, after 9 years, I scavenged all the the parts to replace the missing airbox and the pop is gone!

It might be airbox harmonics, but the rubber coupling also allows the carb to sag slightly which puts the float valve and pivot on the low side of the chamber while the idle bypass port is on the high side.  The sag isn't much, but I think it plays a role.

There is also evidence of oil burning on the left plug and wonder if that would have happened with the stock paper filter setup.

I strongly prefer the stock airbox w/ paper element.  They work great on both the LMIII and the V65 Monza.

[rocker59]

I've run a K&N filter in the stock airbox of my 1996 Sport 1100 for almost 20-years.  Same one.  I clean it and oil it every now and again.  Has worked well for me. 

Everyone says they flow more and filter less.  Don't really know, but back in the day everyone who added FCRs and Staintunes also added K&N filters.

I run stock paper filters on everything else.

[jacksonracingcomau]

No experience testing stock lm4 box and carbs
But did plenty of dyno and road testing with velocity stacks, open, k&n pods and foam uni filters
Uni outperform k&n in every way except cleanliness from outside, white trousers not advised.
The only k&n filter I would use with phm40 carbs is the kit for vhb T3 etc, needs modding but has much beigger surface area, know of a few bikes with these that work well.
Me, I stick to Uni, last 100,000 mile service using these needed rings but not pistons or guides
Cheap, easy to clean and reuse, jet for, no carb sag

But comments re modern airboxes prob not relevant to op, mk4 box different kettle of fish
My advice dyno run or test on road 60mph roll on against known quantity bike, pref std same
Std filter
Std box no filter
Uni foam pods
Big k&n kit for T3 etc
I would be surprised if foam did not win but this way absolute proof

[egschade]

15K RPM multi that needs all the air it can get? May make sense. Waste of money on a low RPM engine like a Guzzi. Just keep the paper one and replace when dirty.

[lazlokovacs]

beetle, thanks for the post, really exactly what I was asking for. Thank you for taking the time.

jackson, great info from great experience

cheers everyone else too, good stuff

ta

[redrider90]

I installed SS Agostini's + Euro jetted and installed a high flow K&N filter in the stock box of my Mille. It had a noticeable increase in performance and pulled a lot harder though out the full RPM scale. Although I never tested its top end. I get to the ton and that's it for me so I do not know if the top end increased.  It also dropped the stock 55/57 mpg fuel consumption by 5 mpg. Agostini recommended opening up the air filter and euro jetting with their exhaust. They said I would eat the top end of the motor if I left the carbs and air filter stock.

[LowRyter]

The K&N flow better and probably filter less.  The dirtier the filters get, the better they filter and less they flow.  I've not determined any difference in performance but I do think it's much more convenient to be able to clean the filter instead of buying a new one. 

And on some bikes, there may not be a filter available after many years.  I realize that's not true for Guzzis but for some bikes.